Screech/squeal under load

[AMink]

I am geting a squeal or screech under load when pulling hills. It only seems to happen when the fan engages. When the pitch of the fan changes so does the squeal. It kind of comes and goes bit seems to be getting worse. It never happens running empty, only pulling. Today my temp gauge got almost to the red which has never happened before. It was hot and the hill is a long grind. Pulled over and it cooled quickly. Any thoughts? Is there a bearing in the fan clutch?

 

[Hoefler]

May be time for a new belt and/or tensioner.

 

[AMink]

May be time for a new belt and/or tensioner.

Will the belt make a metallic sqeal? I hope so! I did replace the belt a while ago but not the tensioner.

 

[Hoefler]

Possible bearing going bad in the idler and/or tensioner

 

[seafish]

You should simply check EACH and EVERY pulley bearing that the serpentine belt runs around for excessive play and/or tightness. The PS pump is the only pulley that might have some in/out play and still be OK...all others should spin freely with no roughness, looseness or tightness.

 

[Bob4x4]

Don't forget to check the fan hub bearing,it is beefy but they do fail

 

[JR]

I chased a metallic sounding chirp for a couple of weeks, literally went through every bearing as well as replaced a few components that were original for preventative measure. As a last resort I changed the belt and the noise went away. Just guessing that my old belt was glazed or hardened causing the noise. I don't think it will resolve your overheating issue (unlesss it was severely slipping) but something to keep in mind if your belt has some time on it.

 

[AMink]

Chasing this down. Fan clutch was toast. Replaced. Still squeal. Vacuum pump was failing. Replaced. Still. Changed a/c compressor as it had a wobbly pulley. Having work done a very reputable shop. They've checked hoses, clamps, gaskets...what a PIA.

 

[JR]

Do you have a spare belt? You may be surprised....

If the AC compressor doesn't do the trick I would definitely throw another belt on, regardless of age of the current belt. I know I'm repeating myself from my above post but it cured what ailed me. I never would have believed someone if they told me the noise I was hearing was my belt.

 

[mwilson]

Have they checked the water pump???

 

[petersonj]

I never would have believed someone if they told me the noise I was hearing was my belt.

JR has a good point here. Over the years as a mechanic by trade, I have heard all kinds of abnormal sounds that were actually emitted by the belt on all kinds of vehicles. Some of these sounds ranged from mechanical knocking sounds to screeching sounds and pretty much everything in between. Some of the sounds that I heard I would have said that there was no way it could have been coming from the belt - but I was wrong.

For example, just the smallest amount of coolant leaked unwittingly onto a belt can make some horrendous sounds under certain conditions.

- John

 

[AMink]

I don't think they pulled it but they did check all pulleys. The pump is relatively new but that doesn't mean much. The vacuum pump was pretty new too.

 

[AMink]

I have a short belt, no vacuum pump, that I can give a try. On the other hand if I'm going to change a belt I'lll get a new one that goes around everything!

 

[WalterJ]

AMink...What was it? Belt, some pulley?

 

[AMink]

AMink...What was it? Belt, some pulley?

I don't think it was the belt or pulley since I had most of those replaced. It's still doing it and I believe it is the gasket between the manifold and turbo. I have a small leak (after 3 gaskets!) and I think it acts much as a reed on a saxophone. The air gets pushed through the leak and vibrates the gasket. Not 100% but that's my best guess. Thanks for reminding me, I need to start a thread about the leak!

 

[WalterJ]

My terrible under hood squeal was a new (8 month) NAPA Premium belt, that proved to be too hard to run the flat side upon the fan & pump pulleys. No doubt it would last 100K miles, but my old, albeit softer, spare did the trick. However...

thank goodness I had installed replacement Crank Vibration Damper p/n #ATI-917374, MANUF # 917374, o.d.=7.8", 3 O-Ring shell designed for easy "rebuilding/repair"; smaller than OEM Dia designed to permit changing serpentine belt without removing damper!

...and we found belt could not be removed past the tensioner pulley without loosening it substantially. What up with that? OEM tensioner replaced 2 yrs ago, so only replacements are goofy or OEM's too?

Luck with your whistle prob.